Soluble sugar is an important quality trait in food‐grade soybeans [Glycine max (L.) Merr.]. Desirable sugars such as sucrose, glucose, and fructose can help improve the taste and flavor of soyfood including tofu, soymilk, and natto; whereas oligosaccharides including raffinose and stachyose are indigestible by humans and animals and often cause flatulence or diarrhea. In this study, 241 plant introductions (PIs) of three maturity groups (MGs) from 28 origins were investigated for seed sugar content including glucose, fructose, sucrose, raffinose, and stachyose. Variation was detected in individual and total sugars in soybean PIs from different origins and MGs. Sucrose and stachyose are the major sugars in soybean seed. The sucrose content ranged from 1.6 to 95.4 mg g−1 with 13 PIs containing greater than 70 mg g−1 and 14 PIs having less than 10 mg g−1 The stachyose content ranged from 0.2 to 69.6 mg g−1 with 14 PIs containing less than 10 mg g−1 stachyose. The high sucrose and low stachyose types are the most valuable for breeding specialty soybeans for soyfood and animal feed. In addition, 30 PIs were identified as having high concentrations of glucose or fructose as major sugars. This new class of high glucose or fructose has not been reported before. While soybean germplasm with unique sugar profiles may be useful for future breeding and genetic research, environmental effects on sugar stability will need to be further investigated.

did not infect any of the resistant cultivars. However, the most virulent strain, G7, infected all cultivars tested Soybean mosaic virus (SMV) causes one of the most destructive and caused necrosis in Marshall, Ogden, Kwanggyo, and viral diseases in soybean [Glycine max (L.) Merr.] worldwide. Ninetyeight SMV isolates identified in the USA have been classified into Buffalo and mosaic symptoms in Davis and York. seven strain groups (G1-G7). Three independent loci (Rsv1, Rsv3, Various sources of SMV resistance have been identiand Rsv4) have been identified for SMV resistance. Multiple resisfied in soybean. Several gene symbols have been astance alleles have been reported for the Rsv1 and Rsv3 locus. The signed for the SMV-resistance alleles identified in the objective of this research was to group diverse soybean genotypes on USA. There are three independent loci reported so far the basis of their differential reactions to SMV strains. SMV strains for SMV resistance, Rsv1, Rsv3, and Rsv4. Eight resis-G1 and G7 were used to characterize the reactions of 212 soybean tance alleles have been identified at the Rsv1 locus, genotypes to SMV. Fifty-five genotypes were resistant to G1 but namely, Rsv1 in PI 96983, Rsv1-t in Ogden, Rsv1-y in susceptible to G7, and virus was detected in G7-inoculated plants. York, Rsv1-m in Marshall, Rsv1-k in Kwanggyo, Rsv1-r Thirty-one genotypes were resistant to G1 but exhibited stem-tip in 'Raiden', Rsv1-h in 'Suweon 97', Rsv1-s in LR1, and necrosis following G7 inoculation. These 86 soybean genotypes presumably carry alleles at the Rsv1 locus. Thirty-seven genotypes were Rsv1-n in PI 507389 (Buss et al., 1997; Buzzell and Tu, resistant to G1 and G7, and SMV was not detected by ELISA, indicat-1989; Chen et al.; Kiihl ing that they probably carry Rsv4, Rsv1-r, or Rsv1-h or a combination and Hartwig, 1979;Ma et al., 1995 Ma et al., , 2003. Two alleles of two resistance genes Rsv1Rsv3, Rsv1Rsv4, or Rsv3Rsv4. Seven for SMV resistance have been reported at the Rsv3 genotypes were susceptible to G1 but resistant to G7 and may carry locus; one was identified in OX 686 soybean line derived alleles at the Rsv3 locus. PI 507389 and PI 61944 developed stemfrom the cultivar Columbia (Buzzell and Tu, 1989), and tip necrosis after inoculation with G1 and a mosaic symptom when the other was found in L29 soybean derived from the inoculated with G7, indicating that PI 61944 may carry the same cultivar Hardee (Buss et al., 1999). The Rsv4 locus was Rsv1-n gene as PI 507389. Eighty soybean accessions developed moidentified in a breeding line V94-5152 derived from PI saic symptoms when inoculated with G1 or G7 because of the lack 486355 ϫ 'Essex' and was shown to confer resistance

Five soybean [Glycine max (L.) Merr.] cultivars, PI96983, ‘Ogden’, ‘York’, ‘Marshall’, and ‘Kwanggyo’, were studied to determine the inheritance of their resistant (R) or necrotic (N) reactions to soybean mosaic virus (SMV) strains G4, G5, G6, G7, and G7A. Each parent was crossed reciprocally with a susceptible (S) cultivar (‘Essex’ or ‘Lee 68’) to determine the number of genes for resistance or necrosis. The R parents were also crossed with each other to test the allelism of the genes conditioning the R or N reaction. All the F2 populations from N × S crosses segregated in a 3:1 ratio with necrosis being dominant to susceptibility. The absence of S segregants in F2 populations of N × N and R × R crosses and the lack of segregation in S × S crosses indicate that the single dominant genes in the five non‐susceptible parents are alleles at a common locus. All R × S crosses produced a combination of R, N, and S plants and gave a good fit to a 3(R + N):1S ratio. Two different SMV‐strain × resistance‐gene interactions were observed to produce the N reaction: (i) alleles which are necrotic to specific strains in the homozygous state are dominant to alleles which are resistant or susceptible to the same strain, (ii) alleles which are resistant in the homozygous state to a strain often exhibit necrosis when they occur in a heterozygote with a susceptible allele.

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Sugar content in soybean [Glycine max(L) Merr.] seed is an important quality attribute for soyfood and feed. Rapid extraction and quantification of soluble sugars in soybean seed are essential for large-scale breeding selections. In this study, using water as extractant combined with a high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) system, variability and repeatability of sugar content were tested in 20 diverse soybean genotypes. Individual sugars were clearly resolved and identified, including sucrose, stachyose, raffinose, glucose, fructose, and verbascose. Analysis of variance (ANOVA) revealed a highly reproducible estimation of sucrose, stachyose, and raffinose. PI 243545 was confirmed as a unique germplasm with the highest sucrose (105.48 mg/g) and total sugar (148.76 mg/g) content. Two low-oligosaccharide accessions, PI 200508 and 03CB-14, were confirmed with extremely low concentrations of raffinose and stachyose. PI 417559 was identified as a high glucose and fructose germplasm. The identified germplasm with unique sugar profiles will be valuable in breeding specialty soybeans for improved sugar content. The sugar testing method will facilitate the screening of seed sugar profiles in a large-scale soybean breeding program.